Due to the broad impact of MSTN on myogenesis, fat metabolism and glucose metabolism, high levels of myostatin have been shown to lead to muscle wasting that is associated with a variety of diseases, such as cancer [29], HIV infection [30], liver disease [31], obesity, insulin resistance and type II diabetes [24, 32, 33]. Here, MSTN is linked to obesity due to melanocortin 4 receptor deficiency.